Carburetor



Aug. 22, 1933. R EmsoN 1,923,429

CARBURETOR Filed Jan. "7, 1933 Mg. 551C501).

IN VEN TOR A TTORNEY 55 rice the air bleed valve one} associated Patented Aug. 22, 1933 iTED sTATss -ATENT OFFICE.

CABBUEETOR This invention. relates to ceituretors end. ticulurly to accelerating pure 3S for carburetors. in previous devices of this lziriti it has teen cus-= tomary to provide 2. main fuel supply device, ca,

5 noble of supplying the required rotio of fuel in proportion to the sir which flows through the carburetor at all normal constant operating sceeols. For purposes of acceleration, a. pump was provided. This pinup was eroieoriiy connected to the throttle valve, or to e suction device con trolled by the depression above time throttle; tiittt is, the suction prevailing between the throttle valve and the intake manifold of the engine. Tnese pumps ordinarily have inlet end outiet valves, and operate upon an opening movement oi the throttle to discharge a pro-determined quantity of fuel into the mixing conduit.

Euclo devices were subject to the objection that when the carburetor was operated at nigh speeds, the current of air flowing tit-rough the mixing-3 conduit set up It suction out the discharge nozzle of the accelerating pump. suffieient to cause it com timious discharge through the pump as long es the high speed was maintained. This resulted in e waste of fuel, and undue enrichment of the mixture, loeceuse the nozzle is already celi. breted to give just the right emount of t'uei. The condition cemiot ice corrected by merely evicting spring pressure to hold the inlet or outlet valves closed, for that WO'LIICi interfere with eucceleretiou under certain conditions. it WGlJlki not be convenient or practical to calibrate the main fuel supply device in such warmer es to give just the right amount of fuel to: ewicie open throttle low speed operation and then to errenee to have this ratio suddenly out down, just at the point where the pump nozzle begins to-tiiscfootse by suction.

it is on object of this invention to provide es device oi the above deseribeo elm-rccter in which the pump nozzle will be prevented irom discharg ing by suction at high speeos.

Uther objects and advantages will appear from the following description and accompanying drewins", referring tovvhiclo:

Figure 1 is o diagrammatic reoresentetion of o certuretor embodying my invention.

l lgure 2 is e. sectional view on o, larger soole showing the air bleed valve and the associuted costs.

Figure 3 is a view similar to Figure 2 except that the parts are in e. oifletent operating posttiou.

Figure 4 is an end view of the plug which certoss. Serial 1%. tsetse;

(on. tel-st;

Figure s shows o.- siieiitw modified form oft time device.

Referring to the chewing tile reicreuce numemi 1 indicates the mixing conduit of e carburetor of previousl This mixing conduit is provided with on oil" item 2, e venturi 3, mixture fissile-me outlet t, flange 5 by moons of which. the cotouretor is stteclieoi to the intake manifold of on internal comoustion engine, at throttle velve (i mouuteo on slooit 'l is provided.

The air 11cm 2 is promoted with to choke veive it, mounted on she-it 9, which shett is adopted to to operated by so arm it. is lost motion connection it, connecting the throttle one. voives, is G provided to insure era movement of choke valve vl iieneveithe throttle oioscei or fully opened, without prevent-i213 opezu= tier; of the choke when the is cs1 intermeoiete position.

A flout chemo-er lit in which feet is tamed at e constant level [er-it by ais mounted; in conventiooel rotation to time oerburetor. Fuel is supplied to the courts-mt ievei chomloer by e.- conduit 15 couteolleci. by vslve inoiceteti, time conventionol vent it for the upper port ot the flout chemioer. [i recite? mm 18 mount/sci on pivot it is cosmos mile. the throttle by meeos of link one term 21 is fitted; to the theft "5.

The eccelerotiug pump eompslses o cviiutiei' till, bovine a. piston 23 thei'eiri, which. is ccemecmri to the rocker-em it by meansoi e rec-l it. Time conveutionoi iniet and outlet volves to oust re spectlvelv ere provided for the pump cylinder, coal the outlet valve to discourses. into a. conduit 2t, Whifih is connected. to nozzle 2%, -vviiicii nestle cllsclierges into the mixing conduit ou -rior to e veuturl 3.

It will lee understood, oi? coomse, the ventusi 3 is represeutotive of e, construction in either one, two or three veuturis my cc but it is desiro'olc thfiiti the ucceiemting poms should discherce euterior to tiic goo t of restriction in the mixing conduit.

At the junction of the messages it 23, which is mdioeteo by the reference uumerst 29, e. valve retaining plug so is inset-mo in the body of the carburetor. This plug is attached by means of conventlonul screw threecis 31 end is provides; with e. screw driver slot 32, by means of which it may be eoplied or removed. it gasket 33 is provided to prevent leakage. Tile piug is provided at its lower end with a comparatively large bore 34:, to in a shudder which terms lmovm coostructiou.

a valve seat 35, and a small bore 36, which connects the bore 34 with a cross passage 37. The cross passage 3'7 terminates in annular recess 38, which communicates with return passageway 39 leading back to the constant level chamber.

The valve 4i) is made of fibre or other very light material, preferably a fibre or other. material whichis fioatable in gasoline. vThis valve is held in the bore 34 by means of the retaining member 41 which is firmly pressed into the bore, the retaining member is perforated as indicated so as not to interfere with the flow of air from passageway 39 into passageway 28, whenever the valve is in its open position as indicated in Figure 3. It will be noted that the valve 40 is mounted in a plane at an acute angle-to the horizontal so that in operation when the valve and valve seat become wet with fuel, the fuel will be drained of! down to the lower edge of the valve and from there down the sides of the bore 34 so as to the tendency of the valve to stick in closed position, being held there by the surface tension of the fuel.

It may be noted that the main source of fuel supply comprises nozzle 42, and idle port 43 which are supplied with fuel from the constant level chamber by means of passage 44, chamber 45,and idle tube 46. The idle tube communicates with the chamber by means of port 47, which is slightly above the fuel level in the constant level chamber, and a conventional idle adjusting screw constitute a high restriction to the flow of fuel,

while permitting the admissionof sufiicient air to relieve the suction at 28 and 29, at least to such an extent as to prevent the withdrawal of fuel from the float chamber through thepump pas- 88.865.

The operation of the device is as follows:

For constant speed operation, the carburetor operates in the conventional manner, the proper amount of fuel being applied by the idle port 43, and the main nozzle 42, either separately or together, according to the speed at which the carburetor is operated. Whenever the throttle 6 is opened the piston 23 descends into cylinder 22 and discharges fuel through outlet check valve 26 and passageways 27 and 28. The pressure existing in the passageway 23, of course, tends to cause a discharge of fuel through passages 36 and 37 into passage 39 which leads back to the constant level chamber, but the fibre valve 40, being made extremeiy light, seats against the shoulder or valve seat 35 with the first upward movement of gasoline, thereby preventing any substantial flow of gasoline into the passageway 36 and communicatingpassageways.

As soonas the pressure in the passage 27 is relieved by discharge throughpassageway 28, the valve iii-drops down to its lower position indicated in Figure 3. In case the valve should be inclined to stick to its seat due to the surface tension of the gasoline, the suction applied at the discharge outlet of the nozzle 28 will pull the valve downwardly and unseat it.

When the carburetor is operated at high speed, that is to say when a very large amount of air is flowing through the mixing conduit, developing substantial suction therein, there will be 8.

constant flow of air through the passageway 39 into passageways 3'7, 36, and 34, thereby substantially relieving the suction at the junction 29 of passageways 27 and 28, so that no gasoline will be withdrawn by suction from the constant level chamber through the pump. In case the valve 35 should fail to operate properly, the leakage will return to the float chamber through the passage 39, so that no fuel will be spilled on the outside of the carburetor.

It will be understood that in the construction of the inlet anddischarge valve for the accelerating pump these valves and their springs if any are made as light as possible and arranged to open under extremely low pressures. Frequently ordinary ball check valves, mounted in vertical passages, seated by gravity only, are used and it will be understood that with such valves very little'suction would be required to draw gasoline through the pump to the pump discharge nozzle. with this construction, however, even a very small bleed of air through passages 39, 37 and 36 is suflicient to relieve the suction so that no fuel will be discharged through the pump nozzle except when the pump is operated.

With the construction shown in Figure 5, the fuel from the pump is discharged in a divided stream, one stream passing through the highly restricted discharge nozzle 28, and another and preferably smaller stream returning to the fioat chamber through the still more highly restricted passage 3637A3839. When the pump is not in operation the suction is relieved at the discharge nozzle in the same way as in the device shown in Figures 1 to 4 inclusive. 1

I claim:

1. In a carburetor, a mixing conduit, a throttle valve at the outlet of said mixing conduit, a venturi anterior to said throttle, an accelerating pump discharging into said mixing conduit anterior to said throttle and said venturi at a point of low suction, a constant level chamber, and a valve controlled passage leading from the upper part of said constant level chamber to the discharge outlet of said pump.

2. In a carburetor, means forming a mixing conduit, main fuel supply devices for supplying a substantially constant ratio of fuel to said mixing conduit during constant speed operation, an accelerating device discharging into said mixing conduit at a point of low suction anterior to said main fuel supply device, a constant level fuel chamber, a passageway connecting said accelerating device and said constant level fuel chamber, said passageway being above the level of fuel in said chamber, and a check valve for permitting air to fiow from said constant level fuel chamber to said accelerating device, but to prevent the return flow of air to said constant level chamber.

3. In a carburetor, a mixing conduit, a throttle valve, an accelerating pump for discharging fuel into said mixing conduit upon opening movements of said throttle valve, a constant level chamber for said carburetor, said accelerating device receiving its fuel from said constant level chamber, the discharge outlet of said accelerating device extending to a point above the level of fuel in said constant level chamber, a venting passageway, a check valve for admitting air from 145 said venting passageway to the discharge outlet of said accelerating device, said check valve seating in an upward direction, and being constructed of substantially fioatable material and being adapted to seat and thereby prevent the dis- 1,oas,ssc

charge of fuel from said accelerating device into said vent eway.

4. In a carburetor, means forming a mixing conduit, an accelerating pump, said pump having a discharge passageway leading into said mixing conduit, a valve controlled vent in said discharge passageway, said vent having a valve of light weight material adapted to be floated and moved to closedposition by liquid fuel.

5. In a carburetor means forming a mixing conduit, said mixing conduit having a discharge outlet, a throttle valve controlling said discharge outlet, main fuel supply devices for supplying the normal requirements of fuel to said carburetor during constant speed operation, a constant level fuel chamber for supplying fuel to said main fuel supply device, a throttle operated accelerating pump also receiving fuel from said constant level chamber, said pump having a discharge passageway extending to a point substantially above the level of fuel in said constant level chamber, and having a discharge outlet in said mixing conduit, a vent at a point in said discharge passageway above the fuel level in said constant level chamber, a fibre valve controlling said vent and a passage connecting said vent with the upper part of the constant level chamber.

6. In a down draft carburetor of the plain tube type, a mixing conduit having a throttle controlled outlet, means including a venturi within said conduit and forming a zone of high suction anterior of said throttle, a main fuel supply device discharging at a point within said zone of high suction and delivering the proper amount of fuel to said mixing conduit during high speed operation, a constant level fuel supply chamber,

an accelerating pump, a discharge conduit for said pump having a restricted outlet discharging into said mixing conduit at a point of low suction anterior to said venturi, a vent for said discharge conduit at a level substantially higher than the level of fuel in said constant level chamber and higher than the discharge outlet, and a valve for controlling said vent.

7. In a down draft carburetor of the plain tube type, a mixing conduit having a throttle con trolled outlet, a venturi mounted within said conduit anterior to said throttle, a constant fuel supply chamber, an accelerating pump, a discharge conduit for said pump having a restricted outlet discharging into said mixing conduit at a point of low suction anterior to said venturi, a vent for said discharge conduit at a level substantially higher than the fuel level in said chamber and higher than the discharge outlet, and a valve for controlling said vent, said valve being of the flat platetype and being mounted in a plane at an acute angle to the horizontal whereby the tendency of said valve to be held in closed position by the surface tension of the fuel will be minimized 8. In a carburetor, a mixing conduit having a restriction therein, said restriction forming a zone of high suction, a main fuel supply device discharging within said zone, an accelerating pump, a constant level fuel chamber supplying both said main fuel supply device and said accelerating pump, said accelerating pump having a discharge passageway extending upwardly to a point substantially higher than the level of fuel in said constant level chamber and having a valve controlled vent at said point, said discharge eonduit extending downwardly a substantial distance from said vent and having an outlet within said mixing conduit in a zone of low suction anterior to said zone of high suction.

9. In a carburetor, a mixing conduit having a restriction therein, said restriction forming a zone of high suction, a main fuel supply device discharging within said zone, an accelerating pump, a constant level fuel chamber supplying both said main fuel supplydevice and said accelerating pump, said accelerating pump having a discharge passageway extending upwardly to a point substantially-higher than the level of fuel in said constant level chamber and having a valve controlled vent at said point, said discharge conduit extending downwardly at an angle from anoaan n. meson. 

